Imagination and duct tape can solve more than you give it credit for.
eek I...I got it!? Wow, that was a random guess! Um, let me try for reasoning:
Perhaps if I hadn't been around
there would have been just one
Um, I think this means that if Cho hadn't been around, there would have been only one girl Harry really liked.
I kept rash company
but I never did condemn
These are the lines that pulled me towards my answer. Cho's friend - what's her name? - ratted out the D.A. - the rash company - but she never really did anything wrong herself.
And at Hogwarts school
I'm the only representative mentioned
The only idea I have for this is that Cho is a supporter of the Tornados Quidditch team, and she was the only one really mentioned throughout the books
That's the best reasoning I have considering I just guess and I really didn't expect it to be right...
(_____/)
(=0 _ 0=)
(‘’)____(‘’)
I likes da bunny! ☮

Internets please?